Z1OwnersClub GB

i am about to do the vavle clearances on my newly rebuilt z1b head, all new guides,vavles,and cam bearing halves.i will set them up with the head off the bike to start, what im asking is can they be ground down? i am an engineer and have access to a surface grinder so it would save me time and money if i can simply reduce the thickness where needed? also any ideas on what to set them at to start? i know they will close up as the vavles bed in also how many miles after i start using the bike will they have to be re-checked? any assistance greatly received. graham

Hi, you can take a bit off the valve stems, but not off the shims as they're hardened & may break up if mucked with! Do a search as I'm sure this has been covered a while ago
Once set, recheck after 500 miles as its a new head, to be safe
Set 'em at the top limit of the tolerance, 0.004" in old money, cold

You can grind a small amount off the valve stems as per the factory manual but it's a last resort to get you back into shimming range if your valves clearances have tightened up so that you can't get correct clearances with the thinnest ones available. If you're a paid up club member call Jerry for a shim swopping service, the ones you don't need for the ones you do.

If you grind shims down as Pigford says they're hardened it'll weaken them - the last thing you want is shims breaking in your engine....

Personally I'd set them to 4-6 thou for initial set up. There is a service bulettin from '76 ish to dealers to open gaps up to 6 thou to give better performance. And no, they don't rattle at 6 thou.

Jerry wrote:And no, they don't rattle at 6 thou.

Not if you are wearing ear-plugs

I've set mine 5-6 Thou.....with no probs..better off loose than tight....
I said that..not the WIFE.
Plus the fact it ticks over better, with a smoother acceleration,
so I agree with The Prez